The invention relates to a control device for an alternating-current motor operating in single-phase and having at least a first and a second winding, one coupled with the other such that they are shifted in phase with respect to each other, comprising a line connection, a first and a second winding connection for the first and the second winding, respectively, of the alternating-current motor, a control unit including a first and a second switching element located between the line connection and the first and the second winding connection, respectively, one of the switching elements being open in a switching state of the control unit, depending on the running direction of the alternating-current motor, and the other being closed, and at least one of the switching elements being open in a state of rest of the control unit, and a power supply unit for making electric energy available for the control unit.
In the control devices known so far, it has always been necessary for the power supply unit to have both the phase and the neutral conductor leading to the control device in order that the power supply unit is capable of constantly supplying the control unit with the necessary electric energy. If such a control device is to replace an electromechanical switch which is already available and which only switches, for example, the phase onto one of the winding connections of the electric motor, there is the problem that in addition to the line for the phase and the lines for the two winding connections, the neutral conductor has to be linked up in order to ensure that this control device is constantly supplied with power independently of operation of the alternating-current motor. Problems arise particularly when this is to be carried out within the scope of a home installation, more particularly, using an available socket installed when the building was constructed.